New close control adiabatic humidifier

The new Condair DL in-duct adiabatic humidifier offers the accurate humidity control normally only available from steam humidifiers, but with the low energy performance and evaporative cooling benefit of a cold water system. It also incorporates many anti-microbial features that make it one of the most hygienic humidifiers available.

The Condair DL is a hybrid humidifier that combines spray and evaporative technologies to maximise moisture absorption and provide humidity control at ±2%RH. A water treatment system provides pure water to a grid of nozzles located inside the duct. The nozzles spray towards a ceramic droplet separator, which has the dual action of preventing aerosols from travelling down the duct and offering secondary evaporation through its porous surface. This increases efficiency of the system with 95% of the spray water evaporating during both processes.

The spray nozzles initially operate in stages to meet a required output and humidity demand. Following the initial stage control, fully modulating control is then achieved by increasing the water pressure to the nozzles. By responding to humidity demand and output control in this way, the humidifier can deliver the type of humidity accuracy typically only available from a steam humidifier.

The humidifier incorporates an RO water treatment system that ensures only pure water is introduced to the AHU. It then treats the pure water with a patented silver ionisation process that actively inhibits microbial growth and has a residual effect throughout the humidifier. Flush and drain cycles prevent water from remaining in the system to stagnate and optional compressed air drying guarantees moisture cannot remain in the humidifier’s water lines. In addition to these features, optional H2O2 disinfection can be incorporated into the system and initiated via the control panel.

All these features make it one of the most hygienic humidifiers in the world and have earned the unit accreditation by the SGS Institut Frensenius in Germany for hygienic operation. The system was independently tested under real-life operating conditions for a six-month period. Part of the investigation included purposeful microbial contamination to assess the effect. Throughout the test the Condair DL fulfilled all requirements and outperformed the VDI 6022 industry standard for microbial growth, achieving a maximum CFU/ml microbial count 85% less than the recommended limit.

The Condair DL offers both the control accuracy of electric steam humidifiers and extremely hygienic operation but without the high electrical energy costs. By pre-heating the airstream prior to the Condair DL with gas-fired heating, the same volume of moisture can be absorbed by the air as steam humidification provides, but at one third the energy cost due to the economy of gas. If a building’s waste heat can be used for the pre-heating process, the humidification energy savings are even greater.

As with all adiabatic humidifiers, the Condair DL also offers the additional benefit of evaporative cooling during the warmer months. As 1kg of absorbed moisture provides 0.68kW of evaporative cooling to the air, the Condair DL can provide over 680kW of cooling per hour from as little as 1kW of consumed electrical energy.